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Current guideline was developed in frameworks of ComTraForce project 18SIB08 and provides recommendations and standards for force calibration of testing machines under dynamic force taking into account parasitic influences from multi-component forces and temperature effects., The ComTraForce project 18SIB08 has received funding from the European Metrology Programme for Innovation and Research (EMPIR) as well as the European Association of National Metrology Institutes (Euramet).

DKD guidelines are application documents regarding the DIN EN ISO/IEC 17025 requirements. The guidelines contain a description of the technical, process-related and the organizational procedures which accredited calibration laboratories use as a model for defining internal processes and regulations. DKD guidelines may become an essential component of the quality management manuals of calibration laboratories. By implementing the guidelines, it is ensured that the devices to be calibrated are all treated equally in the various calibration laboratories and that the continuity and verifiability of the work of the calibration laboratories are improved. The DKD guidelines should not impede the further development of calibration procedures and processes. Deviations from guidelines as well as new procedures are allowed in agreement with the accreditation body if there are technical reasons to support this action. Calibrations by accredited laboratories provide the user with the security of reliable measuring results, increase the confidence of customers, enhance competitiveness in the national and international markets, and serve as metrological basis for the monitoring of measuring and test equipment within the framework of quality assurance measures. This guideline is the first official working draft (WD23-03) which has been developed within the 18SIB08 ComTraForce project coordinated by PTB Braunschweig. The project has received funding from the EMPIR programme co-financed by the participating states and from the European Union’s Horizon 2020 research and innovation programme., The ComTraForce project 18SIB08 has received funding from the European Metrology Programme for Innovation and Research (EMPIR) as well as the European Association of National Metrology Institutes (Euramet).

The aim of this work is to develop guidelines for the calibration of material testing machines with continuous force under consideration of parasitic influences. The focus is set on influencing quantities that play a major role in calibrations with continuous force., The ComTraForce project 18SIB08 has received funding from the European Metrology Programme for Innovation and Research (EMPIR) as well as the European Association of National Metrology Institutes (Euramet).

In der Arbeit wird über einen neuartigen Sensors zur Langzeitmessung von Dehnungen in Bauwerken berichtet. Mit Hilfe des Sensors sollen die für eine langfristige Überwachung benötigten Informationen über die mechanische Belastung des Bauwerks ermittelt werden. Langzeitmessungen mittels DMS scheiterten jedoch in der Vergangenheit an ihrer Empfindlichkeit gegenüber klimatischen Einflüssen. Deshalb wurde ein gekapselter Aufnehmer entwickelt, mit dem die Dehnungszustände in einer kleinen Messbohrung in der Baukonstruktion gemessen werden. Dabei ist die DMS-Technik im Sensorinneren geschützt. Da vergleichbare Messverfahren bisher nicht bekannt sind, musste zunächst ein geeignetes Sensorprinzip entwickelt werden. Eine Analyse verschiedener Adaptionskonzepte führte zur optimalen Form als vieleckiger, vorgespannter Federkörper. Die für die Fixierung im Bauwerk notwendige Vorspannung wird durch den Aufbau aus zwei ineinander verspannten, gleichsinnig konischen Körpern erzeugt. Ein eigens entworfener Mehrfachgitter-DMS mit drei Wheatstoneschen Brückenschaltungen ermöglicht die Messung aller drei Komponenten des ebenen Dehnungszustands. Um den DMS im Sensorinneren vor klimatischen Einflüssen zu schützen, wurde eine geeignete Kapselung entwickelt und in Langzeituntersuchungen mittels dazu erstellter Prüfverfahren erprobt. Mit Hilfe eines speziellen Kalibrierkörpers lässt sich eine Übertragungsmatrix zwischen den Dehnungskomponenten und den Messsignalen bestimmen. Die Einsatzfähigkeit des Sensors für die Bauwerksüberwachung wurde an Ersatzbauwerken durch experimentelle Simulationen typischer Schadensszenarien überprüft. Dabei konnten Schäden schon im Frühstadium erkannt werden., The paper reports on the development of a novel sensor for long-term measurement of strains in structures. This sensor shall provide information on the mechanical loading state of the structure required for long-term surveillance. In the past, long-term measurements have failed due to the sensitivity of the strain gauges to climatic influences. Therefore an encapsulated sensor has been developed which allows the strain states inside a structure to be measured and which protects the sensitive strain gauge technique inside its housing. As comparable measuring procedures have not been known so far, first of all an appropriate sensor principle had to be developed. A comprehensive analysis of different adaptation concepts finally furnished the optimal form of a polygonal prestressed spring. The arrangement of two bodies tensed up within each other and conical in the same direction allows the pre-stress required for fixing in the structure to be generated. With its three Wheatstone full-bridge wirings, the specially designed multiple-grid strain gauge allows all three unknown components of the plane states of strain to be measured. To protect the strain gauge inside the sensor against climatic influences, a suitable encapsulation was developed and tested in long-term tests. Specially elaborated test procedures allow a reliable prognosis for the useful life to be made. A special calibration body allows a transformation matrix between the components of strain and the measuring signals to be determined. Usability of the sensor for structural surveillance was investigated by experimental simulations of typical damage scenarios on dummy structures. The sensor allowed damages to be recognized already in an early stage.